Hi,
I just joined this forum and am currently working on power supplies for tube mics... I know this is an old thread but it has been resurrected so I'll just add my 2 cents...
I was given an AKG power supply that needed a complete rebuild for a C60 mic. The voltages required are 4 volts for the AC701 filament and 120 volts for the B+ supply.
What I ended up doing is using a couple of 3 terminal regulators to regulate both voltages. For the B+ voltage, I used a LT783 regulator which works well for the 120 volt B+.
The filament supply needs something that either ramps up slowly or a constant current regulator, which basically does the same thing. As luck would have it, the LM317 can be configured as a current source. See attached pic.
Has anyone used these regulator configurations for old tube mics? I don't see any drawbacks but please chime in if I'm overlooking something.
The advantage of using regulated supplies is a super quiet noise floor.
I just joined this forum and am currently working on power supplies for tube mics... I know this is an old thread but it has been resurrected so I'll just add my 2 cents...
I was given an AKG power supply that needed a complete rebuild for a C60 mic. The voltages required are 4 volts for the AC701 filament and 120 volts for the B+ supply.
What I ended up doing is using a couple of 3 terminal regulators to regulate both voltages. For the B+ voltage, I used a LT783 regulator which works well for the 120 volt B+.
The filament supply needs something that either ramps up slowly or a constant current regulator, which basically does the same thing. As luck would have it, the LM317 can be configured as a current source. See attached pic.
Has anyone used these regulator configurations for old tube mics? I don't see any drawbacks but please chime in if I'm overlooking something.
The advantage of using regulated supplies is a super quiet noise floor.